1. Field of the Invention
The invention relates generally to the art of railway signaling and communication. More particularly, the invention relates to the use of a dynamic vehicle operating characteristic measurement and control system effectively operative in real-time to optimize scheduling and flow of vehicle traffic.
2. Description of the Prior Art
Vehicle traffic control systems for railway and transit installations interconnect the central train control ("CTC") facility to wayside equipment such as switch and signal devices. To prevent the establishment of conflicting routes and to optimize scheduling based on the available equipment, such systems incorporate means to detect the presence of vehicles within the controlled territory. Typically, this train detection capability has been provided by the railway track circuit. The railway track circuit basically detects the presence of a railway vehicle by electrical alteration of a circuit formed by the rails and the vehicle wheel and axle sets. While there are many variations, railway track circuits are generally connected within fixed-location, fixed-length sections of track route known as blocks. Blocks may range in length from hundreds of feet to a maximum of approximately two to five miles. While these systems can positively detect the presence of a railway vehicle within the particular block, it cannot be particularly located therein. Thus, location resolution of such track circuits is generally defined by the length of the block.
Alternative train operation systems have been proposed which require more accurate train detection than may be provided by present track circuits. Specifically, the promulgation of the Advanced Train Control System ("ATCS"), the introduction of high speed train technology, and the need to optimize scheduling and energy utilization have established a requirement to measure the position of a railway vehicle effectively in real-time and on the order of one meter. It is also desirable to have real-time information concerning motion and grade status of the individual vehicles.
Currently, to provide accurate vehicle information such as position, motion and attitude in effective real-time for a land transportation application having a widely-varied dynamic environment requires reliance on satellite tracking systems such as the global position system, dead-reckoning systems, or installation of wayside mounted sensing systems. These systems may not be able to provide such information in mountainous terrain, tunnels or other geographical regions which inhibit their effective operation.